Well after giving it another try I realized what I didn't like about 'Happy Ending', the chorus...bleh. Those 'eeeh's are almost unbearable, but the rest of the song's alright.
As for Humming 7/4, the other song I hated before, I still hate it, flower garden is so much better for Ayu's end-of-the-album track/bonus track, this song is just yucky.